Bridge plugs are often introduced or carried into a subterranean oil or gas well on a conduit, such as wire line, electric line, continuous coiled tubing, threaded work string, or the like, for engagement at a pre-selected position within the well along another conduit having an inner smooth inner wall, such as casing. The bridge plug is typically expanded and set into position within the casing. The bridge plug effectively seals off one section of casing from another. Several different completions operations may commence after the bridge plug is set, including perforating and fracturing. Sometimes a series of plugs are set in an operation called “plug and perf” where several sections of casing are perforated sequentially. When the bridge plug is no longer needed the bridge plug is reamed, often though drilling, reestablishing fluid communication with the previously sealed off portion of casing.
Setting a bridge plug typically requires setting a “slip” mechanism that engages and locks the bridge plug with the casing, and energizing the packing element in the case of a bridge plug. This requires large forces, often in excess of 20,000 lbs. The activation or manipulation of some setting tools involves the activation of an energetic material such as an explosive pyrotechnic or black powder charge to provide the energy needed to deform a bridge plug. The energetic material may use a relatively slow burning chemical reaction to generate high pressure gases. One such setting tool is the Model E-4 Wireline Pressure Setting Tool of Baker International Corporation, sometimes referred to as the Baker Setting Tool.
After the bridge plug is set, the explosive setting tool remains pressurized and must be raised to the surface and depressurized. This typically entails bleeding pressure off the setting tool by piercing a rupture disk or releasing a valve.